The present invention relates generally to an improved traffic light control apparatus, and more particularly to a control apparatus for a network traffic light.
The conventional control manner of previous traffic lights or traffic control signals is characterized by a switching circuit within the control box which sends a plurality of light signals to corresponding lamps at an intersection via their respective power lines. Such an intersection traffic light requires many control power lines. Thus, it is high in cost, is not easy to install, and is difficult to maintain and repair.
FIG. 1, shows the above-described traffic light system which comprises a main control box 100, sixteen control lines 30, and four light devices 21, 22, 23, and 24, each connected to the main control box 100 via four respective control lines 30. Such a traffic light system has several drawbacks:
1. A plurality of control lines are needed. Thus, it is difficult to install, and the cost is relatively high. PA1 2. If parts of the control lines are broken during road works, the operation of all light devices in the same system will be affected. PA1 3. The main control box is so complicated that maintenance is difficult and time-consuming. PA1 first single-chip microprocessor capable of making control decisions, and encoding/decoding the communication signal; PA1 first power line carrier communication circuit coupled with the first microprocessor and the power transmission lines for receiving output communication signals from the first microprocessor and then loading it onto the power transmission lines; and for unloading input communication signals from the power transmission lines and then inputting it into the first microprocessor; PA1 a display device and key-in circuit coupled to the first microprocessor for displaying the operation state of the network traffic light and for inputting a sit signal keyed in by a user into the microprocessor; and PA1 a power line filter coupled to the power transmission lines to avoid power line harmonic interference. PA1 second single-chip microprocessor capable of controlling the ON/OFF states of the lamps, and encoding/decoding the communication signal; PA1 second power line carrier communication circuit coupled between the second microprocessor and the power transmission lines for receiving output communication signals from the second microprocessor and then loading them onto the power transmission lines and for unloading the input communication signal from the power transmission lines and then inputting it into the second microprocessor; PA1 a plurality of solid-state relays coupled between the second microprocessor and the lamps respectively actuated by the second microprocessor to turn the lamps; on/off and PA1 a plurality of lamp-failure detecting circuits coupled between the second microprocessor and the lamps for detecting operation failure of the lamps.
Therefore it is desirable that the prior traffic light system should be improved.